1. Field
The disclosed embodiments relate to a di-tert-butylphenyl alkylsulfonate compound, tert-butylphenyl alkylsulfonate compound, di-tert-butylphenyl arylsulfonate compound and tert-butylphenyl arylsulfonate compound useful as an intermediate material of a pharmaceutical, agricultural chemical, electronic material or polymer material and the like, or as a battery material, to an nonaqueous electrolytic solution for a lithium secondary battery having superior cycle performance and other battery properties through the use of a nonaqueous electrolytic solution for a lithium secondary battery that uses the above-mentioned compounds, and to a lithium secondary battery using the above-mentioned compounds.
2. Related Art
In recent years, lithium secondary batteries have come to be widely used as power supplies for driving compact electronic devices and the like. Lithium secondary batteries are mainly composed of a positive electrode and negative electrode containing materials capable of occluding and releasing lithium, and a nonaqueous electrolytic solution containing a lithium salt. Examples of these nonaqueous electrolytic solutions include carbonates such as ethylene carbonate (EC) or propylene carbonate (PC).
Known examples of materials used for the negative electrode of lithium secondary batteries include lithium metal, metal compounds capable of occluding and releasing lithium (such as simple metals, oxides or alloys of lithium), and carbon materials. Among carbon materials in particular, nonaqueous electrolyte secondary batteries are widely used and employ a carbon material capable of occluding and releasing lithium such as coke or graphite (artificial graphite, natural graphite). In lithium secondary batteries using highly crystallized carbon materials, such as natural graphite or artificial graphite in particular, EC or PC and the like used for the nonaqueous electrolyte solvent are known to cause a decrease in battery performance due to the occurrence of partial electrochemical reductive decomposition on the negative electrode surface during the course of repeated charging and discharging.
Moreover, studies have been conducted on negative electrodes using materials other than lithium metal or carbon materials, such as tin or silicon for the negative electrode material. However, since tin alloys or silicon alloys that have occluded lithium are highly active, carbonic acid esters present in the electrolytic solution end up being decomposed, while also resulting in the problem of deactivation of the occluded lithium.
On the other hand, since lithium secondary batteries using materials such as LiCoO2, LiMn2O4, LiNiO2 or LiFePO4 for the positive electrode exhibit a high voltage of 3.5 V or more accompanying insertion and extraction of lithium ions based on lithium as a reference, batteries having a high energy density are able to be obtained. Conversely, due to the high voltage, decomposition products cause a decrease in battery performance due to the local occurrence of partial oxidative decomposition in the case the solvent in the nonaqueous electrolytic solution has reached a high temperature during charging. This is thought to be caused by an electrochemical oxidative decomposition reaction at the interface between the positive electrode material and nonaqueous electrolytic solution.
As previously stated, when an electrolytic solution decomposes on the positive electrode or negative electrode, gas is generated and the battery swells or electrolytic solution decomposition products become adhered to the electrodes, thereby causing a decrease in cycle performance and other aspects of battery performance.
Under such circumstances, in electronic devices in which lithium secondary batteries are installed, power consumption increases and capacity continues to rise, resulting in an environment in which decomposition of the electrolytic solution occurs even more easily, thereby resulting in the problem of further exacerbation of cycle performance and other battery properties.
Although Japanese Patent Application Laid-open No. H04-160766 discloses a lithium secondary battery in which benzene triflate (phenyl trifluoro methanesulfonate) and xylene triflate are dissolved in a nonaqueous electrolytic solution, satisfactory cycle performance is still unable to be obtained despite using these compounds.